Acid-Catalyzed Intramolecular Imination / Nucleophilic Trapping of 4-Aminobutanal Derivatives: One-Pot Access to 2-(Pyrazolyl)pyrrolidines

Article abstract of DOI:10.1002/ejoc.201900868

A first successful synthesis of 2-(pyrazolyl)pyrrolidines is reported starting from readily available reagents. A wide variety of N-substituted 2-(pyrazolyl)pyrrolidines are obtained with up to 96 % yield. The influence of the obtained compounds on biofilm formation by V. aquamarinus DSM 26054 and A. calcoaceticus VKPM B–10353 have been studied. Some of the tested compounds were found to suppress the growth of bacterial biofilms at nanomolar concentrations and thus are promising candidates for further studies.

Full text of DOI:10.1002/ejoc.201900868

A Journal of
Accepted Article
Title: Acid-catalyzed intramolecular imination / nucleophilic
trapping of 4-aminobutanal derivatives: one-pot access to 2-
(pyrazolyl)pyrrolidines.
Authors: Andrey V Smolobochkin, Tanzilya S Rizbayeva, Almir
Gazizov, Julia K Voronina, Alexey B Dobrynin, Anastasiya
V Gildebrant, Anna G Strelnik, Ivan S Sazykin, Alexander R
Burilov, Michail A Pudovik, and Marina A Sazykina
This manuscript has been accepted after peer review and appears as an
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of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201900868
Link to VoR: http://dx.doi.org/10.1002/ejoc.201900868
Supported by

10.1002/ejoc.201900868
European Journal of Organic Chemistry
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Acid-catalyzed intramolecular imination / nucleophilic trapping of
4-aminobutanal derivatives: one-pot access to 2-
(pyrazolyl)pyrrolidines.
Andrey V. Smolobochkin,[a] Tanzilya S. Rizbayeva,[a] Almir S. Gazizov,*[a] Julia K. Voronina,[b] Alexey B.
Dobrynin,[a,c] Anastasiya V. Gildebrant,[d] Anna G Strelnik,[a] Ivan S. Sazykin,[d] Alexander R. Burilov,[a]
Michail A. Pudovik[a] and Marina A. Sazykina[d]
Abstract: A first successful synthesis of 2-(pyrazolyl)pyrrolidines is
reported starting from readily available reagents. A wide variety of N-
substituted 2-(pyrazolyl)pyrrolidines are obtained with up to 96% yield.
The influence of obtained compounds on the biofilm formation by V.
aquamarinus DSM 26054 and A. calcoaceticus VKPM B-10353 have been
studied. Some of the tested compounds were found to suppress the
bacterial biofilms growth at nanomolar concentrations and thus are
promising candidates for further studies.
Introduction
Pyrrolidine ring is an important structural part of many natural
alkaloids1–4 and one of the most frequently occurring heterocyclic
scaffolds in approved drugs.5 In recent years, the number of 2-
diazole substituted pyrrolidine derivatives patented as drugs
increased sharply, indicating growing interest in the practical
application of such compounds. Examples are antiviral drugs
Velpatasvir6 and Daclatasvir7 used in the treatment of hepatitis C
infection, anti-cancer drugs Acalabrutinib8 (approved by FDA in
2017) (Figure 1).
Figure 1. Approved drugs containing 2-(diazolyl)pyrrolidine moiety.
[a]
Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan
Scientific Center, Russian Academy of Sciences
420088, Arbuzova str., 8, Kazan, Russian Federation
E-mail: agazizov@iopc.ru
However, despite the increasing number of research aimed at
obtaining and study of 2-(hetaryl)pyrrolidines, synthesis of these
compounds meets certain difficulties. Approaches to these
compounds can be divided into two main groups (Scheme 1). The
first one includes the modification of an existing pyrrolidine
fragment. Various cross-coupling reactions of heteroaromatics
with appropriately substituted pyrrolidine derivatives,9–14 including
oxidative15–17 and photooxidative ones,18–21 are the most often
[b]
[c]
[d]
N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS
31 Leninsky Av., 119991 Moscow, Russian Federation
Kazan National Research Technical University
420111, 10 Karl Marx Str., Kazan, Russian Federation
Southern Federal University
344090, 194/2, Stachki Avenue, Rostov-on-Don, Russian
Federation
Supporting information for this article is given via a link at the end of
the document
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10.1002/ejoc.201900868
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used within this pathway. Synthesis of enantiomerically pure 2-
(hetaryl)pyrrolidines in several cases has been also accomplished
by decarboxylative heteroarylation of proline derivatives.22–28
The second approach to the 2-(hetaryl)pyrrolidines is based on
the formation of pyrrolidine ring from acyclic precursors. Within
this approach, the intermolecular [3+2] dipolar cycloaddition of
activated alkenes to azomethine ylides plays a significant role.29–
33 The activation of alkene double bond is achieved by introducing
an electron-withdrawing substituent – a carboxyl, carbonyl, or
nitro group, in fewer cases – a cyano or trifluoromethyl group.34
As a rule, these reactions proceed with a high degree of
stereoselectivity, which is achieved by employing complex chiral
pyrrolidine derivatives bearing heterocyclic moiety at the 2nd
position of pyrrolidine ring.
Pyrazolones were chosen as substrates for this reaction due to
their significant pharmacological activities44,45 as well as many
possibilities of modification and manipulation for obtaining new
valuable compounds.46,47 Notably, although many 2-(hetaryl)
substituted pyrrolidines have been described, no pyrrolidine
derivatives possessing pyrazolone moiety are known until now.
Thus, herein we report the first succcessful one-pot synthesis of
2-pyrazolyl
intramolecular
substituted
pyrrolidines
via
trapping
acid-catalyzed
of 4,4-
imination / nucleophilic
diethoxybutyl-1-amine derivatives with various pyrazolones.
Either C- or N-alkylation of the pyrazolone derivative may occur
depending on its nature. The proposed approach benefits from
mild reaction conditions, simple work-up procedure and usage of
readily available starting materials and catalysts.
metal catalysts. As
a
typical example, the 1,3-dipolar
cycloaddition of glycine imines to (E)-3-phenyl-1-(1H-pyrazol-1-
yl)prop-2-en-1-one in the presence of a chiral Ag(I) complex35 can
be mentioned.
Results and Discussion
We initiated our studies with the screening of the reaction
conditions for the interaction of 3-methyl-1-phenyl-pyrazol-5-one
1a with 1-(4,4-diethoxybutyl)-3-phenylurea 2a. The results are
summarized in Table 1. First, we have tried conditions previously
found36 to be optimal for the reaction of urea 2a with phenols.
However, the reaction of pyrazol-5-one 1a with urea 2a in
chloroform in the presence of 1 equivalent of trifluoroacetic acid
led to the bispyrrole derivative 4 as the only product (Table 1,
entry 1). The formation of this compound may be explained by the
intramolecular imination of the urea 2a and subsequent
dimerization of dihydropyrrole derivative thus formed, as
described by us previously.48 The same result was obtained when
the trifluororacetic acid was used as the solvent (Table 1, entry 5).
Carrying out the reaction in ethanol and water in the presence of
excess of hydrochloric acid or one equivalent of trifluoroacetic
acid allowed us to obtain the desired 2-pyrazolylprrolidine 3a,
albeit in low yield (Table 1, entries 2-4). The yield of target
compound 3a increased up to 60% when acetic acid was
employed as the solvent and catalyst (Table 1, entry 6). The
similar yield was achieved in benzene in the presence of
trifluoroacetic acid (Table 1, entry 7). In all cases, the formation of
bispyrrole 4a was the competing reaction. However, it could be
suppressed by diluting the reaction mixture, thus allowing us to
obtain the 2-pyrazolylprrolidine 3a with up to 95% yield (Table 1,
entries 8, 9). The substitution occurs at the fourth position of
pyrazolone ring, which is confirmed by the absence of C4-H
proton in 1H NMR spectra of the compound 3a as well as 2D NMR
data.
Scheme 1. Synthesis strategies to 2-(hetaryl)pyrrolidines.
Essential drawbacks of above mentioned approaches are the
need in expensive metal catalysts and/or harsh reaction
conditions, as well as the need of preliminary synthesis of starting
compounds with appropriate functional groups and desired
hetaryl fragment. Hence, methods employing non-expensive,
readily available reagents and catalysts and allowing
simultaneous pyrrolidine ring closure and C-Chetaryl bond formation
are of a special interest.
Earlier, we have developed the metal-free approach to the 2-
arylsubstitued pyrrolidine derivatives based on the acid-catalyzed
intramolecular imination of 4,4-diethoxybutyl-1-amine derivatives
leading to the formation of pyrrolinium cation. Further Mannich-
type reaction of this cyclic iminium ion with various electron-rich
aromatic nucleophiles allowed us to obtain a range of 2-
arylpyrrolidine derivatives.36–43
With the optimized conditions in hand, we next explored the scope
of ureas 2 with different substituents in the phenyl moiety using
the pyrazol-5-one 1a as the model compound (Table 2, 3a-h).
Electron-donating methoxy group produced the corresponding
product 3b with fairly high yield, whereas electron-withdrawing
carboxyl substituent in aromatic ring decreases the yield of target
compound 3c significantly. This behavior is consistent with our
previous observations36 and can be explained by the decrease of
electron density on the nitrogen atoms, which hinders the
We anticipated that the usage of heterocyclic nucleophiles
instead of aromatics in these reactions should lead to the
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intramolecular imination leading to the formation of pyrrolidine
ring.
3
4
5
6
7
8
9
EtOH (5)
EtOH (5)
TFA (5)
HCl, excess
25
15
TFA, 1 eqiuv
–
Table 1. Optimization of reaction conditions of the pyrazol-5-one 1a and
(4,4-diethoxybutyl)urea 2a[a]
[c]
–
AcOH (5)
C6H6 (5)
C6H6 (20)
C6H6 (30)
–
60
67
80
95
TFA, 1 eqiuv
TFA, 1 eqiuv
TFA, 1 eqiuv
[a] Reaction conditions: urea 3a (1.79 mmol), pyrazol-5-one 1a (1.79 mmol),
r.t., 24 h. [b] According to 1H NMR data. [c] Bispyrrole 4a was isolated as the
only product.
The substrate scope was further tested by utilizing different
substituted pyrazol-5-ones. The pyrazol-5-one possesing methyl
group in aromatic fragment reacted smoothly to give target
compound 3e with 57% isolated yield. In contrast, pyrazol-5-ones
containing nitro- and carboxy- groups in the aryl fragment did not
react at all and were recovered from the reaction mixture
unchanged. The only product isolated in this case was the
bispyrrole derivative 4. Thus, the presence of strong electron-
withdrawing substituents in aromatic ring of the pyrazol-5-one
prevents the reaction. The chloro-substituted pyrazolone reacted
with urea 2a to give product 3f with moderate yield. Similarly,
reaction of ureas 2 with antipyrine resulted in the formation of 2-
(pyrazolyl)pyrrolidines 3g,h.
Entry
Solvent (volume, mL)
СHCl3 (5)
Catalyst
Yield of 3а, %[b]
c
1
2
TFA, 1 eqiuv
HCl, excess
–
H2O (5)
10
Table 2. Trifluoroacetic acid-catalyzed one-pot synthesis of 2-(pyrazolyl)pyrrolidines 3.[a]
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[a] Isolated yield
Next, we extended the scope of this reaction to N-(4,4-
diethoxybutyl)sulfonylamides 5. Sulfonylamides possessing alkyl,
aryl and heteroaryl substituents at sulfur atom reacted smoothly
giving 1-sulfonyl-2-(pyrazolyl)pyrrolidines 3i-q. Yields vary
somewhat, and no straightforward influence of the substituent on
the yield of the target compounds was detected. According to 1H
NMR data, 2-ethoxypyrrolidines 6 were formed as byproducts.
Again, reaction of pyrazol-5-ones containing electron-withdrawing
groups in the aryl fragment didn’t result in target compounds
formation and 2-ethoxypyrrolidines 6 were the only products.
Notably, no such compounds were observed in case of N-(4,4-
diethoxybutyl)ureas 2.
We supposed that 2-ethoxypyrrolidines 6 could be intermediates
in the 2-(pyrazolyl)pyrrolidines formation as is the case with 2-
arylpyrrolidines previously described by us.42,49 To check this
hypothesis, we carried out the reaction of pyrazol-5-one 1a with
2-ethoxypyrrolidines 6o,p. The reaction proceeded in the
refluxing benzene in the presence of 1 equivalent of trifluoroacetic
acid to give the pyrrolidines 3o,p with 50-63% isolated yield
(Scheme 2).
Scheme 2. Reaction of 2-ethoxypyrrolidines 6o,p with pyrazolone 1a.
On the basis of the above investigations and previous reports,42,49
we propose a plausible mechanism of 2-(pyrazolyl)pyrrolidines 3
formation as shown in Scheme 3. The first stage of the reaction is
the carboxonium ion A formation via protonation of oxygen atom
and elimination of ethanol molecule. Subsequent intramolecular
imination of this cation leads to the iminium ion B through the
intermediate 2-ethoxypyrrolidine 6. 1-Pyrrolinium ion B thus
formed is a highly reactive species and undergoes rapidly two
concurrent reactions. The first one is the interaction with pyrazol-
5-one 1 molecule to give the cation C. Further elimination of
proton results in 2-(pyrazolyl)pyrrolidines 3 formation. These
stages may be considered as intermolecular Mannich-type
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reaction. The other reaction is the deprotonation of the cation B
resulting in enamide D. Subsequent reaction of this intermediate
compound with another iminium cation B leads to the formation of
bispyrrole derivative 4. Obviously, the less a nucleophilicity of the
pyrazol-5-one 1, the more bispyrrole 4 is formed, and vice versa.
Thus, in case of the reaction of N-(4,4-diethoxybutyl)ureas 2 with
pyrazol-5-ones 1 containing electron-withdrawing substituents
second pathway becomes dominant and only bispyrrole 4
formation is observed. However, in case of N-(4,4-
diethoxybutyl)sulfonylamides 5 the reaction stops at the 2-
ethoxypyrrolidines 6 formation. This may be attributed to the
higher electron density on the nitrogen atom in sulfonylamides
compared to ureas,50,51 which stabilizes the iminium cation B and
decreases its deprotonation rate.
isolated in pure form. The formation of compounds 9 is likely to
proceed via Mannich-type reaction of enolized pyrazolidin-3-one
7. Notably, carboxylic acid derivatives, both cyclic and acyclic,
usually require usage of either strong bases52,53 or Lewis
acid/base combination54,55 to undergo the reaction with iminium
ion. To the best of our knowledge, no such reactions in the
presence of Bronsted acid were reported until now.
Table 3. Synthesis of 2-(pyrazolidin-1-yl)pyrrolidines 8.[a]
Scheme 3. Plausible mechanism of 2-(pyrazolyl)pyrrolidines 3 formation and
side reaction leading to bispyrrole derivatives 4.
Next, we tested in these reactions the saturated analog of
pyrazolones,
1-phenylpyrazolidin-3-one
7.
N-(4,4-
diethoxybutyl)ureas 2 produced complex mixture of products,
which could not be separated. In contrast, sulfonylamides 5
reacted smoothly to give 2-(pyrazolidin-1-yl)pyrrolidines 8 (Table
3). Surprisingly, the C-alkylated products 9 was also observed in
1H NMR spectra of reaction mixture, although could not be
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Figure 2. The molecular structure of compound 3h in crystal. Ellipsoids are
shown with 50% probability.
Next, we studied the influence of some synthesized
(pyrazolyl)pyrrolidines on bacterial biofilms formation. The natural
strain V. aquamarinus DSM 26054 and A. calcoaceticus VKPM B-
10353 were chosen as models due to their ability to actively form
biofilms. Microbial biofilms are responsible for the etiology and
pathogenesis of many acute and, especially, chronic bacterial
infections in humans.56 It has been estimated that more than 80%
of diseases of humans and animals are associated with the
presence of stable bacterial communities enclosed in biofilms.57,58
At the same time, the drug resistance of bacteria living in biofilms
is much higher than that of planktonic bacteria.59,60 Thus, one of
the strategies for controlling pathogenic bacteria is to either inhibit
biofilm formation or to degrade biofilms.61 The obtained biological
activity results are summarized in Table 4.
[a] Isolated yield; [b] According to 1H NMR data; [c] Isolated as trifluoroacetate
salt.
The structures of the compounds 3h,m,o and 8e were additionally
proved by x-ray analysis. The molecular structure of compound
3h is given as an example in Figure 2 (See Supporting Information
for details).
Table 4. Biofilm formation (%) by A. calcoaceticus VKPM B-10353 and V. aquamarinus DSM 26054 in the presence of 2-(pyrazolyl)pyrrolidines 3,8 in
reference to control (control=100%)[a]
Entry
Cmpd
3a
Strain
Concentration, M
1×10-9
106,70
5,07*
1×10-8
1×10-7
72,13*
27,04*
71,57*
37,73*
46,39*
106,23
64,32*
61,58*
59,53*
42,07*
1×10-6
77,45*
98,56
83,91
96,99
85,95
195.10*
74,94*
98,13
81,50
97,05
1×10-5
80,97*
82,29
1
2
3
4
5
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
72,88*
64,31*
54,90*
13,97*
40,00*
34,94*
98,04
3b
97,21
90,09*
96,16
25,18*
111.73*
6,08*
3f
114.66*
143.56*
80,92*
77,43
3g
121,79
153,16
90,50*
4,12*
82,83*
61,44*
25,31*
3o
98,58
52,68*
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6
3q
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
A. calcoaceticus VKPM B-10353
V. aquamarinus DSM 26054
98,88
42,61*
59,53
51,51*
110,84
44,50*
85,14
72,43*
137,33
73,21*
83,92
74,35*
87,25
5,01*
7
8b
105,59
14,27*
101,12
29,04*
91,06*
5,17*
47,73*
76,63*
79,08*
27,72*
60,13*
22,85*
59,80*
7,83*
90,71
87,20
8
8e
63,02*
40,97*
69,68*
45,30*
63,96*
46,80*
63,96*
36,90*
48,59*
51,98*
54,83*
77,48
73,98*
101,57
79,36*
101,31
84,80
123,72
81,95
9
8f
90,94
151.69*
96,32
10
11
12
13
8g
102,79
20,71*
108,38
4,08*
97,33
110.97*
80,15
8h
60,46*
38,70*
41,39*
50,63*
49,53*
74,36
74,85*
98,97
81,31
8i*TFA
8j
125.16*
4,23*
63,39*
108.33*
82,08*
107.90*
81,85
117.37*
82,58*
92,97
102,08
87,70
[a]
The solutions of appropriate solvent in ethanol with the same concentration were used as control; eight replicates were done for each treatment and
control; [*] differences compared to the control samples are statistically significant, t-criterion, p<0.05.
According to the data obtained, the most promising candidates for
further studies are pyrrolidines 3a,b,o and 8e,h. The substantial
inhibition of biofilm formation was observed for these substances
in the range of rather low concentrations – 1x10-7-1x10-9M. At 10-
7 and 10-8M the formation of biofilms of both the V. aquamarinus
DSM 26054 and the A. calcoaceticus VKPM B-10353 strains is
inhibited. Besides this, the formation of V. aquamarinus DSM
26054 biofilm is inhibited at nanomolar concentration of these
compounds (Table 4, entries 1,2,5,8,11).
The activity of pyrrolidines 3f and 8f,g,i,j appeared to be
concentration-dependent. Lower concentrations of compound 8i
stimulated the A. calcoaceticus VKPM B-10353 biofilm formation,
whereas at higher concentrations it was suppressed (Table 4,
entry 12). Compounds 3f and 8f,g,i,j promoted the V.
aquamarinus DSM 26054 biofilm formation at high concentrations,
and inhibited it at lower concentrations (Table 4, entries
3,9,10,12,13). Interestingly, pyrrolidine 3f stimulated A.
calcoaceticus VKPM B-10353 biofilm formation at lowest (1×10-
9M) and highest (1×10-5M) concentrations, and suppressed it in
other cases. Although these results seem to be interesting from
theoretical point of view, the multidirectional dose-dependent
effects render these compounds unsuitable for pharmacological
application.
In conclusion, an efficient method for the synthesis of various N-
substituted 2(pyrazolyl)pyrrolidines was developed for the first
time using easily accessible 4-aminobutanal acetals and
pyrazolones as starting materials and an inexpensive
trifluoroacetic acid as catalyst.
A
mechanism involving
intramolecular imination – Mannich-type reaction sequence was
proposed. Some of the some of the synthesized compounds were
found to inhibit a bacterial biofilm formation at nanomolar
concentrations and thus are promising for further studies as
antibacterial substances.
Experimental Section
General
1H NMR and 13C NMR spectra were recorded on Bruker Avance 400
(working frequency 400.1 MHz for 1H, 100.6 for 13C), Avance 500 (working
frequency 500.1 MHz for 1H, 125.8 for 13C) and Avance 600 (working
frequency 600.1 MHz for 1H, 150.9 for 13C) spectrometers in (CD3)2SO,
CDCl3 and CD3OD relative to the residual solvent protons. ESI-TOF mass
spectra were recorded on a AmazonX (Bruker Daltonik GmbH) instrument.
MALDI-TOF mass spectra were recorded on a Bruker ULTRAFLEX III
TOF/TOF instrument (with 2,5-dihydroxybenzoic acid matrix) instrument.
IR spectra were obtained with a Bruker Vector 22 spectrometer. Elemental
analysis was performed on Carlo Erba EA 1108 instrument. Melting points
were determined in glass capillaries with a Stuart SMP 10 apparatus. All
solvents were purified and dried according to standard procedures. N-(4,4-
Conclusions
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diethoxybutyl)ureas 236 and N-(4,4-diethoxybutyl)sulfonylamides 542,62
were obtained according to known procedures.
General procedure for the synthesis of 2-pyrazolylpyrrolidines 3i-q.
To the solution of sulfonylamide 5 (1.79 mmol) in dry benzene (30 ml)
pyrazole-5-one 1 (1.79 mmol) and trifluoroacetic acid (0.204 g, 1.79 mmol)
were added. The reaction mixture refluxed for 5 hours and the solvent was
evaporated under reduced pressure. The residue was washed with diethyl
ether (3x30 ml), filtered and dried in vacuum (10 torr, 10 h, r.t.) to give the
target compounds.
X-ray studies
The X-Ray diffraction data for crystals of compounds 3h,o and 8e were
collected at 296K on a Bruker AXS Smart Apex II CCD diffractometer in
the ω and φ-scan modes using graphite monochromated MoKα (λ
0.71073Å) radiation. The structure was solved by direct method and
refined by the full matrix least-squares using SHELXTL63 program. All non-
hydrogen atoms were refined anisotropically. The positions of hydrogen
atoms were located from the Fourier electron density synthesis and were
included in the refinement in the isotropic riding model approximation. All
figures were made using OLEX2.64
General procedure for the synthesis of 2-(pyrazolidin-1-
yl)pyrrolidines 8a-j. To the solution of sulfonylamide 5 (1.79 mmol) in dry
benzene (30 ml) 5-methyl-1-phenylpyrazolidin-3-one (0.315 g, 1.79 mmol)
and trifluoroacetic acid (0.204 g, 1.79 mmol) were added. The reaction
mixture refluxed for 5 hours and the solvent was evaporated under
reduced pressure. The residue was washed with diethyl ether (3x30 ml),
filtered and dried in vacuum (10 torr, 10 h, r.t.) to give the target
compounds.
Crystal data for 3h: C23H26N4O3, M = 406.48, colorless crystal 0.12 x 0.15
x 0.15 mm, monoclinic, space group P21/c, Z = 4, a = 11.169(3), b =
20.958(5), c = 9.562(3)Å, β = 113.059(3)° , V = 2059.5(9)Å3, ρcalc = 1.311
g/cm3, μ =0.089 mm-1, 18627 reflections collected (±h, ±k, ±l), 4963
independent (Rint 0.0425) and 3058 observed reflections [I ≥ 2\s (I)], 331
refined parameters, R =0.0474, wR2 = 0.1353, max. residual electron
density is 0.198 (-0.166) eÅ-3.
2-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-N-
phenylpyrrolidine-1-carboxamide (3a). Beige solid (0.32 g, 50%), mp
153-154°С. Found: C 69.8; H 6.25; N 15.2. Calc. for С21Н22N4O2: C 69.8;
H 6.1; N 15.4%. IR (KBr): νmax/cm-1 1595, 1638, 2872, 2917, 2971, 3099,
3302. 1H NMR (400MHz, СD3OD/DMSO-d6 90/10): δ 1.93-2.04 (1Н, m,
СН2), 2.12-2.24 (2Н, m, СН2), 2.24-2.35 (1Н, m, СН2), 2.29 (3Н, s, СН3),
3
3.63-3.74 (2Н, m, СН2), 4.90-4.98 (1Н, m, СН), 6.99 (1Н, t, JHH 7.4 Hz,
Crystal data for 3m: C23H27N3O3S, M = 425.54, colorless crystal 0.2 x 0.15
x 0.15 mm, monoclinic, space group P21/n, Z = 4, a = 14.6487(18), b =
8.0198(9), c = 18.938(2)Å, β = 100.040(4)° , V = 2190.8(4)Å3, ρcalc = 1.290
g/cm3, μ = 0.177 mm-1, 28394 reflections collected (±h, ±k, ±l), 4777
independent (Rint 0.087) and 2281 observed reflections [I ≥ 2\s (I)], 275
refined parameters, R = 0.0687, wR2 = 0.2031, max. residual electron
density is 0.31 (-0.32) eÅ-3.
СНAr), 7.24 (2Н, t, 3JHH 8.0 Hz, СНAr), 7.30 (1Н, t, 3JHH 7.4 Hz, СНAr), 7.38
(2Н, d, 3JHH 8.3 Hz, СНAr), 7.47 (2Н, t, 3JHH 7.9 Hz, СНAr), 7.64 (2Н, d, 3JHH
7.6 Hz, СНAr). 13C NMR (150MHz, СD3OD/DMSO-d6 90/10): δ 10.1; 24.5;
31.7; 47.; 51.8; 106.2; 118.8; 120.34; 120.9; 122.6; 126.0; 128.3; 128.8;
136.3; 139.5; 146.6; 155.4. ESI-TOF, m/z: 363 [M+Н]+, 385 [M+Na]+.
2-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-N-(4-
methoxyphenyl)pyrrolidine-1-carboxamide (3b). Beige solid (0.56 g,
80%), mp 162-163°С. Found: C 67.55; H 5.9; N 14.5%. Calc. for
С22Н24N4O3: C 67.3; H 6.1; N 14.3%. IR (KBr): νmax/cm-1 11597, 1635, 2836,
2949, 3067, 3304. 1H NMR (400MHz, СD3OD/DMSO-d6 60/40): δ 1.81-
1.94 (1Н, m, СН2), 2.00-2.10 (2Н, m, СН2), 2.10-2.20 (1Н, m, СН2), 2.17
(3Н, s, СН3), 3.50-3.57 (2Н, m, СН2), 3.64 (3Н, s, ОСН3), 4.79-4.83 (1Н,
m, СН), 6.73 (2Н, d, JHH 9.0 Hz, СНAr), 7.16 (1Н, t, JHH 7.4 Hz, СНAr),
7.20 (2Н, d, 3JHH 8.9 Hz, СНAr), 7.37 (2Н, t, 3JHH 8.0 Hz, СНAr), 7.59 (2Н,
d, 3JHH 7.6 Hz, СНAr). 13C NMR (150 MHz, СD3OD/DMSO-d6 60/40): δ 10.2,
23.9, 30.9, 46.3, 51.2, 54.1, 105.8, 112.9, 119.6, 121.6, 124.9, 127.5,
128.3, 132.1, 136.2, 146.2, 154.6, 154.8. ESI-TOF, m/z: 415 [M+Na]+.
Crystal data for 3o: C25H25N3O3S, M = 447.54, colorless crystal 0.16 x 0.14
x 0.11 mm, triclinic, space group P-1, Z = 3, a = 7.2073(6), b = 15.8405(14),
c = 113.048(5)Å, α = 113.048(5), β = 97.125(5), γ = 95.401(5) ° , V =
1649.1(3)Å3, ρcalc = 1.352 g/cm3, μ =0.180 mm-1, 26524 reflections
collected (±h, ±k, ±l), 14553 independent (Rint 0.0425) and 9838 observed
reflections [I ≥ 2\s (I)], 871 refined parameters, R =0.0589, wR2 = 0.1484,
max. residual electron density is 0.466 (-0.395) eÅ-3.
3
3
Crystal data for 8e: C20H22N3O3S, M = 384.46, colorless crystal 0.12 x 0.15
x 0.15 mm, triclinic, space group P-1, Z = 2, a = 7.3141(16), b = 11.488(3),
c = 12.196(3), α = 78.020(17), β = 74.948(14), γ = 82.012(13)° , V =
964.2(4)Å3, ρcalc = 1.324 g/cm3, μ =0.193 mm-1, 8017 reflections collected
(±h, ±k, ±l), 3767 independent (Rint 0.1039) and 1692 observed reflections
[I ≥ 2\s (I)], 252 refined parameters, R =0.0935, wR2 = 0.2972, max.
residual electron density is 0.566 (-0.447) eÅ-3
Ethyl 4-(2-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)pyrrolidine-
1-carboxamido)benzoate (3c). White solid (0.12 g, 15%), mp 190-192°С.
Found: C 66.50; H 5.9; N 13.0%. Calc. for С24Н26N4O4: C 66.4; H 6.0; N
12.9%. IR (KBr): νmax/cm-1 1596, 1630, 2933, 2979, 3366. 1H NMR
(400MHz, СD3OD): δ 1.36 (3Н, t, 3JHH 6.9 Hz, СН3), 1.94-2.04 (1Н, m, СН2),
2.14-2.25 (2Н, m, СН2), 2.26-2.38 (1Н, m, СН2), 2.30 (3Н, s, СН3), 3.62-
3.78 (2Н, m, СН2), 4.31-4.37 (2Н, m, СН2), 4.91-4.99 (1Н, m, СН), 7.29
(1Н, t, 3JHH 7.7 Hz, СНAr), 7.46 (2Н, t, 3JHH 6.5 Hz, СНAr), 7.53 (2Н, d, 3JHH
Crystallographic data for 3h, 3m, 3o and 8e have been deposited in the
Cambridge Crystallographic Data Centre, CCDC numbers are 1909796,
1918389, 1909797 and 1909798 respectively. Copies of the data can be
obtained, free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, (fax: +44-(0)1223-336033 or e-mail:
deposit@ccdc.cam.ac.UK).
3
3
8.3 Hz, СНAr), 7.62 (2Н, d, JHH 8.1 Hz, СНAr), 7.89 (2Н, d, JHH 8.3 Hz,
СНAr). 13C NMR (150MHz, СD3OD): δ 10.1, 13.3, 24.5, 31.5, 48.5, 52.1,
60.4, 105.9, 117.2, 118.5, 121.0, 123.7, 126.1, 128.8, 129.9, 130.2, 144.5,
146.6, 154.7, 166.7. ESI-TOF, m/z: 435 [M+Н]+, 457 [M+Na]+.
Chemistry
N-hexyl-2-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)pyrrolidine-
1-carboxamide (3d). Beige solid (0.38 g, 57%), mp 144-145°С. Found: C
68.3; H 8.4; N 15.3%. Calc. for С21Н30N4O2: C 68.1; H 8.2; N 15.1%. IR
General procedure for the synthesis of 2-pyrazolylpyrrolidines 3a-h.
To the solution of urea 2 (1.79 mmol) in dry benzene (30 ml) pyrazole-5-
one 1 (1.79 mmol) and trifluoroacetic acid (0.204 g, 1.79 mmol) were
added. The reaction mixture was stirred at room temperature for 24 hours
and the solvent was evaporated under reduced pressure. The residue was
washed with acetonitrile (3x20 ml), filtered and dried in vacuum (10 torr,
10 h, r.t.) to give the target compounds 3.
1
(KBr): νmax/cm-1 1596, 1633, 2924, 2989, 3260, 3326. H NMR (400MHz,
СD3OD): δ 0.88 (3Н, t, 3JHH 6.3 Hz, СН3), 1.22-1.36 (6Н, m, СН2), 1.40-
1.51 (2Н, m, СН2), 1.86-1.99 (1Н, m, СН2), 2.03-2.15 (2Н, m, СН2), 2.19-
2.35 (1Н, m, СН2), 2.24 (3Н, s, СН3), 2.99-3.12 (1Н, m, СН2), 3.15-3.26
(1Н, m, СН2), 3.47-3.59 (2Н, m, СН2), 4.74-4.81 (1Н, m, СН), 7.30 (1Н, t,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900868
European Journal of Organic Chemistry
FULL PAPER
3JHH 7.2 Hz, СНAr), 7.47 (2Н, t, 3JHH 7.8 Hz, СНAr), 7.64 (2Н, d, 3JHH 7.9 Hz,
СНAr). 13C NMR (150MHz, СD3OD): δ 10.1, 13.0, 22.3, 24.1, 26.2, 29.9,
31.3, 32.3, 40.1, 46.6, 51.7, 106.3, 120.7, 126.0 128.8, 136.3, 146.2 157.8.
ESI-TOF, m/z: 371 [M+Н]+, 393 [M+Na]+.
25.4, 31.4, 35.8, 49.7, 54.4, 108.5, 123.7, 126.3, 127.4, 129.3, 130.0,
135.4, 136.0, 143.3, 154.6, 164.0. ESI-TOF, m/z: 412 [M+Н]+, 434 [M+Na]+.
4-(1-(Ethylsulfonyl)pyrrolidin-2-yl)-1,5-dimethyl-2-phenyl-1,2-
dihydro-3H-pyrazol-3-one (3j). White solid (0.32 g, 51%), mp 160-161°С.
Found: C 58.6; Н 6.7, N 12.2; S 9.3%. Calc. for С17Н23N3O3S: C 58.4; Н
6.6; N 12.0; S 9.2%. IR (KBr): νmax/cm-11154, 1593, 1653. 1H NMR (400
MHz, (CD3)2SO): δ 1.12 (3H, t, 3JHH 7.3 Hz, СН3), 1.73-1.85 (1Н, m, СН2),
2.02-2.11 (1Н, m, СН2), 2.11-2.22 (2Н, m, СН2), 2.25 (3Н, s, СН3), 2.91
(2H, q, 3JHH 7.1 Hz, СН2), 3.02 (3Н, s, СН3), 3.34-3.41 (1Н, m, СН2), 3.47-
3.55 (1Н, m, СН2), 4.61-4.69 (1Н, m, СН), 7.28-7.34 (3Н, m, СНAr), 7.44-
7.53 (2Н, m, СНAr). 13C NMR (100MHz, (CD3)2SO): 8.0, 11.0, 26.0, 31.5,
36.0, 44.6, 49.4, 54.0, 108.7, 123.9, 126.5. 129.4, 135.7, 155.0, 164.5.
MALDI-TOF, m/z: 350 [M+Н]+, 372 [M+Na]+, 388 [M+K]+.
2-(5-hydroxy-3-methyl-1-(p-tolyl)-1H-pyrazol-4-yl)-N-
phenylpyrrolidine-1-carboxamide (3e). White solid (0.38 g, 57%), mp
166-167°С. Found: C 70.0; H 6.8; N 14.9%. Calc. for С22Н24N4O2: C 70.2;
H 6.6; N 14.9%. IR (KBr): νmax/cm-1 1597, 1635, 2957, 2982, 3249, 3362.
1H NMR (400MHz, (CD3)2SO): δ 1.80-1.93 (1Н, m, СН2), 2.01-2.09 (2Н,
m, СН2), 2.10-2.20 (1Н, m, СН2), 2.17 (3Н, s, СН3), 2.29 (3Н, s, СН3),
3.55-3.64 (2Н, m, СН2), 4.80-4.88 (1Н, m, СН), 6.83 (1H, s, NH), 7.15-
3
7.25 (4Н, m, СНAr), 7.33 (1Н, m, СНAr), 7.44 (2Н, d, JHH 8.5 Hz, СНAr),
3
7.58 (2Н, d, JHH 8.6 Hz, СНAr). 13C NMR (150MHz, (CD3)2SO): δ 20.9,
25.0, 31.7, 34.7, 47.43 51.9, 106.7, 118.1, 119.8, 122.1, 128.7, 129.1,
129.8, 134.4, 140.9, 146.1, 154.4, 155.7. ESI-TOF, m/z: 377 [M+Н]+, 399
[M+Na]+.
4-(1-((4-Chlorophenyl)sulfonyl)pyrrolidin-2-yl)-1,5-dimethyl-2-
phenyl-1,2-dihydro-3H-pyrazol-3-one (3k). White solid (0.39 g, 50%),
mp 155-156°С. Found: C 58.5; H 5.2, Cl 8.3; N 9.9; S 7.5%. Calc. for
С21Н22ClN3O3S: C 58.4; H 5.1; Cl 8.2; N 9.7; S 7.4%. IR (KBr): νmax/cm-1
1158, 1593, 1656. 1H NMR (400 MHz, (CD3)2SO): δ 1.49-1.60 (1Н, m,
СН2), 1.95-2.05 (2Н, m, СН2), 2.07-2.17 (1Н, m, СН2), 2.27 (3Н, s, СН3),
3.00 (3Н, s, СН3), 3.52-3.64 (2Н, m, СН2), 4.51-4.59 (1Н, m, СН), 7.19
(2H, d, 3JHH = 7.9 Hz, СНAr), 7.28 (1H, t, 3JHH = 7.6 Hz, СНAr), 7.45 (2H, t,
2-(1-(4-chlorophenyl)-5-hydroxy-3-methyl-1H-pyrazol-4-yl)-N-
phenylpyrrolidine-1-carboxamide (3f). Beige solid (0.25 g, 35%), mp
193-194°С. Found: C 63.7; H 5.1; Cl 9.0; N 14.3%. Calc. for С21Н21ClN4O2:
C 63.55; H 5.3; Cl 8.9; N 14.1%. IR (KBr): νmax/cm-1 1598, 1637, 2922,
3426. 1H NMR (400MHz, (CD3)2SO): δ 1.84-1.96 (1Н, m, СН2), 2.05-2.23
(4Н, m, СН2), 2.20 (3Н, s, СН3), 3.55-3.63 (2Н, m, СН2), 4.78-4.90 (1Н, m,
СН), 6.86 (1Н, t, 3JHH 7.4 Hz, СНAr), 7.14 (2Н, t, 3JHH 7.8 Hz, СНAr), 7.36
(2Н, d, 3JHH 8.6 Hz, СНAr), 7.41 (2Н, d, 3JHH 8.1 Hz, СНAr), 7.74 (2Н, d, 3JHH
8.6 Hz, СНAr). 13C NMR (150MHz, (CD3)2SO): δ 12.4, 25.1, 31.5, 47.5,
51.9, 118.1, 119.8, 120.7, 121.4, 122.0, 128.7, 129.0, 129.3, 140.9, 141.0,
154.3, 155.7. ESI-TOF, m/z: 397 [M+Н]+, 419 [M+Na]+, 335 [M+K]+.
3
3
3JHH 7.7 Hz, СНAr), 7.54 (2H, d, JHH 8.5 Hz, СНAr), 7.68 (2H, d, JHH 8.4
Hz, СНAr). 13C NMR (150MHz, (CD3)2SO): δ 11.0, 25.5, 31.3, 35.7, 49.7,
54.4, 107.7, 123.9, 126.5, 129.2, 129.4, 129.6, 135.3, 137.9, 138.3, 154.6,
163.8. ESI-TOF, m/z: 455 [M+Na]+.
N-(4-((2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-
yl)pyrrolidin-1-yl)sulfonyl)phenyl)acetamide (3l). Yellow oil (0.68 g,
87%). Found: C 60.83.17; Н 5.82, N 12.37; S 7.09. Calc. for С23Н26N4O4S:
C 60.78; Н 5.77; N 12.33; S 7.05. IR (KBr): νmax/cm-1 1149, 1598, 1638,
3254. 1H NMR (600 MHz, (CD3)2SO): δ 1.35-1.47 (1Н, m, СН2), 1.85-2.00
(2Н, m, СН2), 2.00-2.09 (1Н, m, СН2), 2.07 (3Н, s, СН3), 2.26 (3Н, s, СН3),
2.96 (3Н, s, СН3), 3.40-3.52 (2Н, m, СН2), 4.43-4.51 (1Н, m, СН), 7.20
(2H, d, 3JHH 7.8 Hz, СНAr), 7.26 (1H, t, 3JHH 7.4 Hz, СНAr), 7.42 (2H, t, 3JHH
2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-N-
phenylpyrrolidine-1-carboxamide (3g). Beige solid (0.46 g, 69%), mp
157-158°С. Found: C 71.0; H 6.2; N 15.0%. Calc. for С22Н24N4O2: C 70.9;
H 6.4; N 14.9%. IR (KBr): νmax/cm-1 1595, 1634, 1662, 2964, 3052. 1H NMR
(400MHz, СD3OD): δ 1.93-2.06 (1Н, m, СН2), 2.15-2.32 (3Н, m, СН2), 2.35
3
(3Н, s, СН3), 3.14 (3Н, s, СН3), 4.89-4.96 (1Н, m, СН), 7.00 (1Н, t, JHH
3
3
7.4 Hz, СНAr), 7.22-7.27 (2Н, m, СНAr), 7.33-7.39 (4Н, m, СНAr), 7.42 (1Н,
t, 3JHH 7.5 Hz, СНAr), 7.52 (2Н, t, 3JHH 7.7 Hz, СНAr). 13C NMR (150MHz,
СD3OD): δ 9.5, 24.7, 31.3, 33.7, 47.2, 52.1, 107.7, 120.4, 122.6, 125.7,
127.7, 128.2, 129.1, 134.2, 139.4, 152.3, 155.4, 164.3. ESI-TOF, m/z: 377
[M+Н]+, 399 [M+Na]+.
7.8 Hz, СНAr), 7.65 (2H, d, JHH 8.3 Hz, СНAr), 7.74 (2H, d, JHH 8.5 Hz,
СНAr), 10.42 (1Н, s, NН). 13C NMR (150MHz, (CD3)2SO): 11.1, 24.4, 25.3,
31.5, 35.6, 49.7, 54.4, 108.2, 119.0, 124.2, 128.5, 129.3, 132.6, 135.2,
143.5, 154.2, 164.0, 169.8. ESI-TOF, m/z: 455 [M+Н]+, 477 [M+Na]+.
1,5-Dimethyl-2-(p-tolyl)-4-(1-tosylpyrrolidin-2-yl)-1,2-dihydro-3H-
pyrazol-3-one (3m). White solid (0.53g, 70%), mp 127-128°С. Found: C
60.5.17; Н 6.5, N 10.0; S 7.6%. Calc. for С23Н27N3O3S: C 64.9; Н 6.4; N
9.9; S 7.5%. IR (KBr): νmax/cm-1 1151, 1598, 1637. 1H NMR (400 MHz,
(CD3)2SO): δ 1.37-1.49 (1Н, m, СН2), 1.87-2.00 (2Н, m, СН2), 2.01-2.14
(1Н, m, СН2), 2.27 (3Н, s, СН3), 2.33 (6Н, s, СН3), 2.97 (3Н, s, СН3), 3.43-
3.50 (2Н, m, СН2), 4.47-4.52 (1Н, m, СН), 7.11 (2H, d, 3JHH 8.3 Hz, СНAr),
7.26 (2H, d, 3JHH 8.2 Hz, СНAr), 7.32 (2H, d, 3JHH 8.0 Hz, СНAr), 7.61 (2H,
d, 3JHH 8.3 Hz, СНAr). 13C NMR (150MHz, (CD3)2SO): 11.2, 21.0, 21.4, 25.4,
31.4, 35.7, 49.7, 54.5, 108.4, 124.0, 127.5, 129.8, 130.0, 133.0, 135.8,
136.2, 143.2, 154.1, 163.9. MALDI-TOF, m/z: 426 [M+Н]+, 448 [M+Na]+,
464 [M+K]+.
2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-N-(4-
methoxyphenyl)pyrrolidine-1-carboxamide (3h). White solid (0.26 g,
36%), mp 113-114°С. Found: C 68.1; H 6.6; N 14.85. Calc. for С23Н26N4O3:
C 68.0; H 6.45; N 14.8. IR (KBr): νmax/cm-1 1608, 1652, 2835, 2949, 3063.
1H NMR (400 MHz, СD3OD): δ 1.89-2.06 (1Н, m, СН2), 2.15-2.30 (3Н, m,
СН2), 2.34 (3Н, s, СН3), 3.14 (3Н, s, СН3), 3.61-3.75 (2Н, m, СН2), 3.76
(3Н, s, СН3), 4.88-4.96 (1Н, m, СН), 6.82 (2Н, d, 3JHH 9.0 Hz, СНAr), 7.25
(2Н, d, 3JHH 8.7 Hz, СНAr), 7.35 (2Н, d, 3JHH 7.5 Hz, СНAr), 7.40 (1Н, t, 3JHH
7.4 Hz, СНAr), 7.51 (2Н, t, 3JHH 7.8 Hz, СНAr). 13C NMR (150MHz, СD3OD):
δ 9.6, 24.7, 31.3, 33.8, 39.5, 52.2, 54.5, 108.0, 113.4, 121.3, 122.8, 125.5,
127.6, 129.0, 134.3, 152.4, 155.8, 156.0, 164.4. ESI-TOF, m/z: 407 [M+Н]+,
429 [M+Na]+, 445 [M+K]+.
N-(4-((2-(1,5-dimethyl-3-oxo-2-(p-tolyl)-2,3-dihydro-1H-pyrazol-4-
yl)pyrrolidin-1-yl)sulfonyl)phenyl)acetamide (3n). White solid (0.49g,
58%), mp 256-257°С. Found: C 61.7.17; Н 6.3, N 12.2; S 7.0%. Calc. for
С24Н28N4O4S: C 61.5; Н 6.0; N 12.0; S 6.9%. IR (KBr): νmax/cm-1 1510,
1592, 1636, 1693, 2928, 3047. 1H NMR (600 MHz, (CD3)2SO): δ 1.36-1.47
(1Н, m, СН2), 1.87-2.00 (2Н, m, СН2), 2.03-2.07 (1Н, m, СН2), 2.08 (3Н,
s, СН3), 2.27 (3Н, s, СН3), 2.33 (3Н, s, СН3), 2.98 (3Н, s, СН3), 3.42-3.50
(2Н, m, СН2), 4.45-4.52 (1Н, m, СН), 7.10 (2H, d, 3JHH 8.3 Hz, СНAr), 7.24
(2H, d, 3JHH 8.0 Hz, СНAr), 7.66 (2H, d, 3JHH 8.8 Hz, СНAr), 7.72 (2H, d, 3JHH
8.9 Hz, СНAr), 10.26 (1Н, s, NН). 13C NMR (150MHz, (CD3)2SO): 11.2,
1,5-Dimethyl-2-phenyl-4-(1-tosylpyrrolidin-2-yl)-1,2-dihydro-3H-
pyrazol-3-one (3i). White solid (0.23 g, 31%), mp 142-143°С. Found: C
64.3; H 6.2; N 10.3; S 7.9%. Calc. for С22Н25N3O3S: C 64.4; H 6.1; N 10.2;
S 7.8%. IR (KBr): νmax/cm-1 1156, 1594, 1658. 1H NMR (400 MHz,
(CD3)2SO): δ 1.37-1.48 (1Н, m, СН2), 1.87-1.98 (2Н, m, СН2), 1.99-2.11
(1Н, m, СН2), 2.28 (3Н, s, СН3), 2.31 (3Н, s, СН3), 2.99 (3Н, s, СН3), 4.44-
4.53 (1Н, m, СН), 7.23 (2Н, d, 3JHH 7.8 Hz, СНAr), 7.28 (1Н, t, 3JHH 7.5 Hz,
СНAr), 7.31 (2H, d, 3JHH 8.1 Hz, СНAr), 7.46 (2H, t, 3JHH 7.7 Hz, СНAr), 7.60
(2H, d, 3JHH 8.0 Hz, СНAr). 13C NMR (100MHz, (CD3)2SO): δ 11.2, 21.38,
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900868
European Journal of Organic Chemistry
FULL PAPER
21.1, 24.6, 25.4, 31.4, 35.6, 49.7, 54.5, 108.3, 118.9, 124.4, 128.6, 129.8,
132.6, 132.9, 136.0, 143.5, 153.9, 163.9, 169.4. MALDI-TOF, m/z: 469
[M+Н]+, 491 [M+Na]+, 507 [M+K]+.
(1H, t, 3JHH 7.3 Hz, СНAr), 7.16 (d, 2H, 3JHH 7.6 Hz, СНAr), 7.16 (2H, t, 3JHH
7.6 Hz, СНAr). 13C NMR (150 MHz, CDCl3) δ: 7.9, 23.5, 29.4, 31.1, 45.0,
48.7, 58.0, 69.3, 119.4, 124.2, 129.2, 152.2, 177.3. ESI-TOF, m/z: 324
[M+Н]+, 346 [M+Na]+.
1,5-Dimethyl-4-(1-(naphthalen-2-ylsulfonyl)pyrrolidin-2-yl)-2-phenyl-
1,2-dihydro-3H-pyrazol-3-one (3o). White solid (0.27 g, 34%), mp 126-
127°С. Found: C 67.3; Н 5.7, N 9.5; S 7.3%. Calc. for С25Н25N3O3S: C
67.1; Н 5.6; N 9.4; S 7.2%. IR (KBr): νmax/cm-1 1154, 1593, 1653. 1H NMR
(400 MHz, (CD3)2SO): δ 1.45-1.55 (1Н, m, СН2), 1.92-2.03 (2Н, m, СН2),
2.03-2.14 (1Н, m, СН2), 2.30 (3Н, s, СН3), 2.88 (3Н, s, СН3), 4.57-4.64
(1Н, m, СН), 6.97 (2H, d, 3JHH 7.9 Hz, СНAr), 7.23 (1H, t, 3JHH 7.5 Hz, СНAr),
7.35 (2H, t, 3JHH 7.7 Hz, СНAr), 7.62 (1H, t, 3JHH 7.4 Hz, СНAr), 7.67 (2H, t,
3JHH 7.7 Hz, СНAr), 7.74 (1H, d, JHH 6.9 Hz, СНAr), 7.99 (1H, d, JHH 8.2
Hz, СНAr), 8.02 (1H, d, 3JHH 8.6 Hz, СНAr), 8.11 (1H, d, 3JHH 8.0 Hz, СНAr),
8.35 (1Н, s, СНAr). 13C NMR (150MHz, (CD3)2SO): 11.2, 25.5, 31.4, 35.6,
49.8, 54.5, 108.0, 123.1, 123.9, 126.4, 127.9, 128.2, 129.1, 129.2, 129.4,
128.6, 129.7, 132.1, 134.7, 135.2, 136.6, 154.4, 163.8. ESI-TOF, m/z: 448
[M+Н]+, 470 [M+Na]+.
2-(1-((2-Chloroethyl)sulfonyl)pyrrolidin-2-yl)-1-phenylpyrazolidin-3-
one (8c). White solid (0,41g, 62%), mp 108°С. Found (%): C 50.5; H 5.7;
Cl 9.8; N 11.8; S 9.0%. Calc. for C15H20 ClN3O3S (%): C 50.4; H 5.6; Cl 9.9;
N 11.7; S 8.96%. IR (KBr): νmax/cm-1 1146, 1595, 1721. 1H NMR (400 MHz,
(CD3)2SO) δ: 1.68-1.80 (2Н, m, СН2), 1.81-1.94 (1Н, m, СН2), 2.03-2.10
(1Н, m, СН2), 2.11-2.17 (2Н, m, СН2), 2.29-2.40 (2Н, m, СН2), 3.22-3.36
(4Н, m, СН2), 3.69-3.86 (4Н, m, СН2), 5.91-5.99 (1Н, m, СН), 7.06 (1H, t,
3JHH 7.3 Hz, СНAr), 7.18 (2H, d, 3JHH 8.0 Hz, СНAr), 7.31 (2H, t, 3JHH 7.7 Hz,
СНAr). 13C NMR (150 MHz, (CD3)2SO)δ: 23.8, 26.8, 29.4, 31.2, 43.8, 46.9,
48.7, 58.0, 69.7, 119.4, 123.9, 129.4, 152.6, 176.3. MALDI-TOF, m/z: 394
[M+Na] +.
3
3
1-Phenyl-2-(1-(phenylsulfonyl)pyrrolidin-2-yl)pyrazolidin-3-one (8d).
White solid (0.49g, 74%), mp 126-127°С. Found (%): C 64.5; H 5.8; N 11.5;
S 8.8%. Calc. for C19H21N3O3S (%): C 61.4; H 5.7; N 11.3; S 8.6%. IR
(KBr): νmax/cm-1 1164, 1597, 1709. 1H NMR (400 MHz, (CD3)2SO) δ: 1.31-
1.47 (1Н, m, СН2), 1.58-1.71 (2Н, m, СН2), 1.71-1.87 (1Н, m, СН2), 2.28-
2.44 (2Н, m, СН2), 3.06-3.15 (1Н, m, СН2), 3.19-3.28 (1Н, m, СН2), 3.68-
3.80 (2Н, m, СН2), 5.67-5.77 (1Н, m, СН), 7.05 (1H, t, 3JHH 7.4 Hz, СНAr),
7.18 (2H, d, 3JHH 7.4 Hz, СНAr), 7.30 (2H, t, 3JHH 7.9 Hz, СНAr), 7.67 (2H, t,
3JHH 7.6 Hz, СНAr), 7.74 (1H, t, 3JHH 7.5 Hz, СНAr), 7.89 (2H, d, 3JHH 7.2 Hz,
СНAr ). 13C NMR (150 MHz, (CD3)2SO) δ: 23.4, 29.4, 30.8, 49.2, 58.1, 69.6,
119.4, 123.9, 127.6, 129.4, 130.0, 133.76, 137.7, 152.6, 176.6. MALDI-
TOF, m/z: 394 [M+Na]+, 410 [M+K]+.
3-((2-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-
yl)pyrrolidin-1-yl)sulfonyl)pyridin-1-ium 2,2,2-trifluoroacetate (3p).
Yellow oil (0.41 g, 58%). Found: C 51.7; H 4.7; N 11.1; S 6.4%. Calc. for
C22H23F3N4O5S: C 51.5; H 4.5; N 10.9; S 6.3%. IR (KBr): νmax/cm-1 1165,
1
1593, 1659. H NMR (400 MHz, CD3Cl): δ 1.82-1.94 (1Н, m, СН2), 2.13-
2.25 (2Н, m, СН2), 2.29-2.36 (1Н, m, СН2), 2.38 (3Н, s, СН3), 3.10 (3Н, s,
СН3), 3.64-3.74 (1Н, m, СН2), 3.74-3.84 (1Н, m, СН2), 4.72-4.79 (1Н, m,
СН), 7.16 (2H, d, 3JHH 7.3 Hz, СНAr), 7.33 (1Н, t, 3JHH 7.5 Hz, СНAr), 7.41-
7.48 (2Н, m, СНAr), 8.17-8.25 (1Н, m, СНAr), 8.58 (1H, d, 3JHH 5.1, 4JHH 1.5
3
Hz, СНAr), 8.84 (1H, d, JHH 1.5 Hz, СНAr). 13C NMR (100 MHz, CD3Cl):
10.8, 25.7, 31.7, 34.8, 49.8, 54.2, 106.6, 124.8, 124.7, 126.4 (q, 1JCF 211.6
Hz), 127.8, 129.3, 133.3, 137.4, 138.1, 145.0, 149.6, 152.2, 159.9 (q, 2JCF
39.3 Hz), 162.8. ESI-TOF, m/z: 399 [M-CF3CO2]+.
1-Phenyl-2-(1-tosylpyrrolidin-2-yl)pyrazolidin-3-one (8e). White solid
(0.66g, 96%), mp 144-145°С. Found (%): C 62.4; H 6.1; N 10.8; S 8.4%.
Calc. for C20H23N3O3S (%):C 62.3; H 6.0; N 10.9; S 8.3%. IR (KBr):
νmax/cm-1 1162, 1596, 1725. 1H NMR (400 MHz, (CD3)2SO) δ: 1.31-1.41
(1H, m, CH2), 1.58-1.67 (2H, m, CH2), 1.71-180 (1H, m, CH2), 2.28-2.38
(1H, m, CH2), 2.40 (3H, s, CH3), 3.01-3.10 (1H, m, CH2), 3.16-3.26 (1H, m,
CH2), 3.70-3.78 (2H, m, CH2), 5.65-5.71 (1H, m, CH), 7.04 (1H, t, 3JHH 7.3
Hz, СНAr), 7.16 (2H, d, 3JHH 7.7 Hz, СНAr), 7.30 (2H, t, 3JHH 7.5 Hz, СНAr),
7.46 (2H, d, 3JHH 8.0 Hz, СНAr), 7.75 (2H, d, 3JHH 8.2 Hz, СНAr). 13C NMR
(150 MHz, (CD3)2SO) δ: 21.5, 21.5, 23.4, 29.4, 30.7, 49.2, 58.1, 69.5,
119.3, 123.9, 127.7, 129.4, 130.4, 134.7, 144.3, 152.5, 176.7. ESI-TOF,
m/z: 408 [M+Na]+.
1,5-Dimethyl-2-phenyl-4-(1-(vinylsulfonyl)pyrrolidin-2-yl)-1,2-
dihydro-3H-pyrazol-3-one (3q). Yellow oil (0.62g, 99%). Found: C 59.0;
Н 6.3, N 12.2; S 9.3%. Calc. for С17Н21N3O3S: C 58.8; Н 6.1; N 12.1; S
9.2%. IR (KBr): νmax/cm-1 1149, 1594, 1659. 1H NMR (400 MHz, CD3Cl): δ
1.79-1.94 (1Н, m, СН2), 2.01-2.25 (2Н, m, СН2), 2.28-2.38 (1Н, m, СН2),
2.32 (3Н, s, СН3), 3.10 (3Н, s, СН3), 3.46-3.60 (2Н, m, СН2), 4.60-4.69
(1Н, m, СН), 5.78 (1H, d, 3JHH 10 Hz, СН), 6.08 (1H, d, 3JHH 16.5 Hz, СН),
2
3
6.41 (1H, dd, JHH 16.5, JHH 9.9 Hz, СН), 7.31-7.34 (3H, m, СНAr), 7.45
(2H, t, JHH 7.8 Hz, СНAr). 13C NMR (100 MHz, CD3Cl): 11.0, 25.5, 31.7,
3
35.7, 49.1, 54.2, 108.1, 125.0, 126.4, 127.6, 128.3, 129.3, 134.0, 152.6,
163.7. ESI-TOF, m/z: 348 [M+Н]+, 370 [M+Na]+.
2-(1-((4-Chlorophenyl)sulfonyl)pyrrolidin-2-yl)-1-phenylpyrazolidin-
3-one (8f). White solid (0.33g, 45%), mp 168°С. Found (%): C 56.3; H 5.1;
Cl 8.9; N 10.5; S 7.8%. Calc. for C19H20ClN3O3S (%): C 56.2; H 5.0; Cl 8.7;
N 10.4; S 7.9%. IR (KBr): νmax/cm-1 1162, 1595, 1731. 1H NMR (600 MHz,
(CD3)2SO) δ: 1.34-1.48 (1H, m, CH2), 1.60-1.83 (3H, m, CH2), 2.28-2.44
(2H, m, CH2), 3.03-3.12 (1H, m, CH2), 3.19-3.28 (1H, m, CH2), 3.71-3.77
(2H, m, CH2), 5.63-5.70 (1H, m, CH), 7.05 (1H, t, 3JHH 7.0 Hz, СНAr), 7.15
(2H, d, 3JHH 7.7 Hz, СНAr), 7.29 (2H, t, 3JHH 7.6 Hz, СНAr), 7.73 (2H, d, 3JHH
2-(1-(Methylsulfonyl)pyrrolidin-2-yl)-1-phenylpyrazolidin-3-one (8a).
White solid (0.47g, 85%), mp 143-144°С. Found (%): C 54.5; H 6.4; N 13.8;
S 10.5%. Calc. for C14H19N3O3S (%): C 54.4; H 6.2; N 13.6; S 10.4%. IR
(KBr): νmax/cm-1 1150, 1593, 1724. 1H NMR (600 MHz, (CD3)2SO) δ: 1.69-
1.82 (2H, m, CH2), 1.86-1.94 (1H, m, CH2), 2.02-2.12 (1H, m, CH2), 2.30-
2.37 (2H, m, CH2), 2.97 (3H, s, CH3), 3.05-3.12 (1H, m, CH2), 3.17-3.14
(1H, m, CH2), 3.73-3.81 (2H, m, CH2), 5.89-5.94 (1H, m, CH), 7.04 (1H, t,
3JHH 7.3 Hz, СНAr), 7.19 (2H, d, 3JHH 7.6 Hz, СНAr), 7.31 (2H, t, 3JHH 7.6 Hz,
СНAr). 13C NMR (150 MHz, (CD3)2SO) δ: 23.9, 29.5, 31.3, 36.0, 48.6, 58.0,
69.9, 119.3, 123.7, 129.3, 152.6, 176.2. ESI -TOF, m/z: 332 [M+Na] +.
3
8.2 Hz, СНAr), 7.87 (2H, d, JHH 8.4 Hz, СНAr). 13C NMR (100 MHz,
(CD3)2SO) δ: 23.3, 29.3, 30.6, 49.2, 58.0, 69.5, 119.3, 124.0, 129.4, 129.5,
130.1, 136.4, 138.8, 152.4, 176.7. ESI-TOF, m/z: 428 [M+Na]+.
N-(4-((2-(5-oxo-2-phenylpyrazolidin-1-yl)pyrrolidin-1-
2-(1-(Ethylsulfonyl)pyrrolidin-2-yl)-1-phenylpyrazolidin-3-one
(8b).
yl)sulfonyl)phenyl)acetamide (8g). White solid (0.73g, 95%), mp 86-
87°С. Found (%): C 58.8; H 5.8; N 13.2; S, 7.9%. Calc. for C21H24N4O4S
(%): C, 58.9; H, 5.7; N, 13.1; S, 7.8%. IR (KBr): νmax/cm-1 1159, 1592, 1695,
2988, 3058. 1H NMR (600 MHz, (CD3)2SO) δ: 1.30-1.41 (1H, m, CH2),
1.56-1.70 (2H, m, CH2), 1.72-1.82 (1H, m, CH2), 2.10 (3H, s, CH3), 2.30-
2.43 (2H, m, CH2), 3.04-3.10 (1H, m, CH2), 3.18-3.24 (1H, m, CH2), 3.69-
3.79 (2H, m, CH2), 5.65-5.73 (1H, m, CH), 7.04 (1H, t, 3JHH 6.8 Hz, СНAr),
7.17 (2H, d, 3JHH 7.6 Hz, СНAr), 7.29 (2H, t, 3JHH 7.3 Hz, СНAr), 7.80 (2H,
White solid (0.36g, 63%), mp 120-121°С. Found (%): C 55.8; H 6.5; N 13.1;
S 9.8%. Calc. for C15H21N3O3S (%): C 55.7; H 6.6; N 13.0; S 9.9%. IR
(KBr): νmax/cm-1 1143, 1593, 1719. 1H NMR (400 MHz, CDCl3) δ: 1.36 (3H,
t, 3JHH 7.4 Hz), 1.69-1.76 (1H, m, CH2), 1.82-1.91 (1H, m, CH2), 1.96-2.07
(2H, m, CH2), 2.36-2.46 (1H, m, CH2), 2.51-2.61 (1H, m, CH2), 3.11 (3H,
q, CH3, 3JHH 7.4 Hz), 3.29-3.38 (1H, m, CH2), 3.43-3.50 (1H, m, CH2), 3.63-
3.70 (1H, m, CH2), 3.95-4.04 (1H, m, CH2), 5.99-6.07 (1H, m, CH), 7.09
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10.1002/ejoc.201900868
European Journal of Organic Chemistry
FULL PAPER
d, 3JHH 8.0 Hz, СНAr), 7.85 (2H, d, 3JHH 8.4 Hz, СНAr), 10.51 (1H, s, NH).
13C NMR (150 MHz, (CD3)2SO) δ: 23.4, 24.5, 24.6, 29.4, 30.8, 49.2, 58.1,
69.6, 117.2, 119.3, 123.8, 128.8, 129.3, 131.1, 144.1, 152.6, 169.7, 176.6.
ESI-TOF, m/z: 451 [M+Na]+.
Test system for biofilm formation evaluation. To quantify the formation
of biofilms, the crystal violet assay with some modifications was used.66
The necessary concentrations of the test compounds were prepared as
described above.
2-(1-(Naphthalen-2-ylsulfonyl)pyrrolidin-2-yl)-1-phenylpyrazolidin-3-
one (8h). White solid (0.55g, 73%), mp 153°С. Found (%): C 65.6; H 5.6;
N 10,1; S 7.7%. Calc. for C23H23N3O3S (%): C, 65.5; H, 5.5; N, 10.0; S,
7.6%. IR (KBr): νmax/cm-1 1157, 1531, 1718. 1H NMR (400 MHz, (CD3)2SO)
δ: 1.28-1.40 (1H, m, CH2), 1.56-1.67 (2H, m, CH2), 1.70-1.80 (1H, m, CH2),
2.25-2.43 (2H, m, CH2), 3.07-3.18 (1H, m, CH2), 3.21-3.31 (1H, m, CH2),
V. aquamarinus DSM 26054 was cultivated for 24 hours in LB medium
supplemented with 3% NaCl in the Innova 40R shaker incubator («New
Brunswick Scientific», USA) at 25°C and 200 rpm. A. calcoaceticus VKPM
B-10353 was cultivated for 24 hours in LB medium in the Innova 40R
shaker incubator («New Brunswick Scientific», USA) at 30°C and 200 rpm.
Then, a suspension of the daily culture was diluted with culture medium to
the density of 3×108 cells/ml (1 MacFarland standart). Turbidity was
measured with DEN-1 («BioSan») instrument.
3
3.70-3.77 (2H, m, CH2), 5.75-5.80 (m, 1H, CH), 7.04 (1H, t, JHH 7.2 Hz,
3
3
СНAr), 7.15 (2H, d, JHH 7.8 Hz, СНAr), 7.28 (2H, t, JHH 7.7 Hz, СНAr),
7.66-7.75 (2H, m, СНAr), 7.89 (1H, d, 3JHH 8.4 Hz, СНAr), 8.06 (1H, d, 3JHH
7.7 Hz, СНAr), 8.17 (2H, t, 3JHH 8.0 Hz, СНAr), 8.49 (1H, s, СНAr). 13C NMR
(100 MHz, (CD3)2SO) δ: 23.4, 29.4, 30.7, 49.3, 58.0, 69.6, 119.3, 122.9,
123.9, 128.3, 128.3, 128.9, 129.3, 129.6, 129.8, 130.1, 132.2, 134.8, 135.0,
152.4, 176.7. ESI-TOF, m/z: 444 [M+Na]+.
The resulting suspension (190 μl) was added to the wells of a polystyrene
microplate ("Nuova Aptaca", Italy). To some of the wells, 10 μl of the test
substances at various concentrations were added. Since solvents used
could also influence the biofilm formation, 10 μl of the appropriate solvent
was added to the other part of the wells at same dilutions. Sterile nutrient
broth was used as negative control. To a part of the 10 μl of deionized
water was added, which was used as a positive control. Eight replicates
were done for each treatment and control. The microplate was covered
with a lid and wrapped with a Parafilm ("Bemis Company, Inc.", USA).
Evaluation of the effect of the studied substances on the biofilm formation
was carried out by comparing the results of the experiment with the
corresponding controls to the solvent.
1-Phenyl-2-(1-(pyridin-3-ylsulfonyl)pyrrolidin-2-yl)pyrazolidin-3-one
(8i). White solid (0.38g, 57%), mp 153-154°С. Found (%): C 58.3; H 5.5;
N 15.1; S 8.7%. Calc. for C18H20N4O3S (%): C 58.1; H 5.4; N 15.0; S 8.6%.
IR (KBr): νmax/cm-1 1170, 1597, 1718, 2992. 1H NMR (600 MHz, (CD3)2SO)
δ: 1.34-1.49 (1H, m, CH2), 1.58-1.69 (1H, m, CH2), 1.72-1.82 (2H, m, CH2),
2.24-2.48 (m, 2H, CH2), 3.15-3.23 (m, 1H, CH2), 3.26-3.34 (m, 1H, CH2),
3
3.69-3.82 (m, 2H, CH2), 3.66-3.73 (1H, m, CH), 7.06 (1H, t, JHH 7.3 Hz,
СНAr), 7.17 (2H, d, 3JHH 7.6 Hz, СНAr), 7.30 (2H, t, 3JHH 7.9 Hz, СНAr), 7.22
(1H, dd, 3JHH 8.7 Hz, 4JHH 4.9 Hz, СНAr), 8.28 (1H, dt, 3JHH 8.1 Hz, 5JHH 1.6
Hz, СНAr), 8.91 (1H, dd, 3JHH 4.8 Hz, 5JHH 1.5 Hz, СНAr), 9.04 (1H, d, 3JHH
2.2 Hz, СНAr). 13C NMR (100 MHz, (CD3)2SO) δ: 23.3, 29.4, 30.6, 49.3,
58.0, 69.5, 119.4, 124.0, 125.1, 129.4, 134.2, 135.7, 148.0, 152.5, 154.3,
176.7. ESI-TOF, m/z: 488 [M+H]+.
After incubation at 25°C for 72 hours (V. aquamarinus DSM 26054) or at
30°C for 24 hours (A. calcoaceticus VKPM B-10353), biofilms were stained.
The contents in the wells were removed by means of a dispenser. The
wells were then carefully washed three times with 250 μl of sterile saline.
The microplates were shaken to remove all non-adherent bacteria.
Biofilms were fixed with 200 μl of 96 % ethanol for 15 minutes.
1-Phenyl-2-(1-(vinylsulfonyl)pyrrolidin-2-yl)pyrazolidin-3-one
(8j).
White solid (0.35g, 62%), mp 104-105°С. Found (%): C 56.2; H, 6.1; N
13.2; S 10.1%. Calc. for C15H19N3O3S (%): C 56.1; H 6.0; N 13.1; S 10.0%.
IR (KBr): νmax/cm-1 1150, 1595, 1734. 1H NMR (600 MHz, (CD3)2SO) δ:
1.62-1.69 (1H, m, CH2), 1.72-1.79 (1H, m, CH2), 1.84-1.91 (1H, m, CH2),
After the microplates had dried in air, 200 μl of 0.5 % crystall violet
prepared according to Hooker67 was introduced into the wells. After 10
minutes, the dye was removed. The excess dye was removed by washing
with 250μl of water three times. After the microplates were air-dried, the
dye in the wells bound to biofilms was dissolved with 200 μl of 96 % ethanol.
The extraction level (absorption) of crystal violet by ethanol was measured
after 60 minutes at a wavelength of 570 nm using a FLUOstar Omega
microplate reader ("BMG Labtech", Germany) in optical density units
(OD570). The intensity of biofilm formation directly corresponds to the
intensity of staining of the contents of the wells with the dye. Biofilm
formation was determined by the difference between the mean OD
readings obtained in the presence of compounds and the control.
3
1.94-2.03 (1H, m, CH2), 2.34 (2H, t, CH2, JHH 7.1 Hz), 3.09 (2H, t, CH2,
3JHH 7.0 Hz), 3.78 (2H, t, CH2, 3JHH 7.1 Hz), 5.76-5.83 (1H, m, CH), 6.12-
6.20 (2H, m, CH2), 6.90 (1H, dd, CH, 2JHH 16.4 Hz, 3JHH 10.1 Hz), 7.05 (1H,
d, 3JHH 7.2 Hz, СНAr), 7.20 (2H, d, 3JHH 7.7 Hz, СНAr), 7.31 (2H, t, 3JHH 7.9
Hz, СНAr). 13C NMR (150 MHz, (CD3)2SO) δ: 23.9, 29.4, 31.2, 48.7, 58.1,
69.9, 119.3, 123.8, 129.2, 129.3, 133.2, 152.6, 176.2. MALDI-TOF, m/z:
344 [M+Na]+.
Biological studies
Each experiment was performed in triplicate. The values were expressed
as mean + SD. Student’s T-test was used to compare these values.
Differences were considered statistically significant at p< 0.05.
Bacterial strains and cultivation conditions. The strain of Vibrio
aquamarinus DSM 26054 and Acinetobacter calcoaceticus VKPM B-
10353 were used to study the biofilms formation. A. calcoaceticus VKPM
B-10353 strain was grown in Luria-Bertani (LB) medium.65 V. aquamarinus
DSM 26054 strain was grown in LB medium supplemented with 3% NaCl.
Acknowledgments
Chemicals. All of the chemicals used were of analytical grade. Сrystal
violet was obtained from «Sigma-Aldrich» (USA). DMSO was obtained
from «Serva» (Russia). Test solutions were prepared immediately before
the tests.
This work was supported by the Russian Science Foundation
(Grant No. 16-13-10023). The authors are grateful to the
Assigned Spectral-Analytical Center of FRC Kazan Scientific
Center of RAS for technical assistance in research. The x-ray
measurements were performed using shared experimental
facilities supported by IGIC RAS state assignment.
Compounds preparation. The test compounds were dissolved in DMSO
to the concentration of 1х10-2 М. Further dilutions were prepared by adding
ethanol. The control solutions were analogous dilutions of DMSO in
ethanol.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201900868
European Journal of Organic Chemistry
FULL PAPER
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